FAA, NASA hone turbulence prediction systems

US regulators and NASA are maturing several onboard technologies that could help airlines avoid in-flight turbulence and at the same time improve weather forecasting.

Most advanced are eddy dissipation rate (EDR) measurement algorithms that the FAA's aviation weather office developed with the Colorado-based National Centre for Atmospheric Research (NCAR). EDR, which uses existing weather radar systems to determine vertical wind currents, provides an aircraft-independent objective measurement of turbulence which is automatically downlinked to airline operations centres.

Whereas voice-based pilot reports are relatively infrequent and subjective, the more frequent automated EDR data reports provide a definitive measurement of the level of turbulence that a particular aircraft is experiencing, a key element for maintenance planning and an input that the FAA says has been proven to improve weather forecasts.

In an effort to bring down the cost of FAA-funded prototype systems now being fielded by Delta Airlines on its 737NG fleet and soon by Southwest Airlines, the FAA is conducting market research to identify manufacturers able to build EDR-based systems that compare favourably to the performance of existing prototype units, but can be built and deployed at lower cost. Responses to the survey are due by 6 August.

NASA, meanwhile, has announced that it is funding the development of a prototype clear-air and severe storm turbulence detection system for remote ocean regions. "The goal is to identify and predict rapidly evolving storms and other potential areas of turbulence," says NASA in a 7 July announcement on the programme.

To be built by NCAR and the University of Wisconsin, the system will use data from a variety of NASA earth-orbiting satellites to give pilots "on select transoceanic routes" real-time turbulence updates.

The spectre of severe weather on such remote routes is a key element in the investigation of the crash of Air France Flight 447, the A330-200 that went down in the South Atlantic off the coast of Brazil on 1 June.

NASA says that when the system is finalised, it will provide pilots and ground-based controllers with text-based maps and graphical displays "showing regions of likely turbulence and storms".